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<div class="moz-cite-prefix">On 7/14/2020 6:14 PM, Wojtek SP9WPN
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:0939ec24-700f-4a29-1ee5-0ba8b3a8558f@gmail.com">W dniu
2020-07-14 o 00:12, Lynn W Deffenbaugh (Mr) wrote:
<br>
<blockquote type="cite">You will receive packets generated by any
station that you have gated from RF to the APRS-IS for some
period of time after you've last gated one of their packets.
Try matching up the stations you're receiving with the packets
being subsequently received back from the APRS-IS.
<br>
</blockquote>
<br>
I'm not sure about this. Most of the stations in question are not
heard directly, but only digipeated to me. This shouldn't count,
should it?
<br>
</blockquote>
<p>The packet originator is all that matters, not who you copied the
packet from. If you gate a packet from a station, even via a
digipeater, to the APRS-IS, you will receive future packets
originated by those stations from the APRS-IS. This is to support
the IGate design details documented at:</p>
<p><a href="http://www.aprs-is.net/IGateDetails.aspx">http://www.aprs-is.net/IGateDetails.aspx</a><br>
</p>
<blockquote type="cite"
cite="mid:0939ec24-700f-4a29-1ee5-0ba8b3a8558f@gmail.com">
<br>
<blockquote type="cite">This is done for several reasons. One is
to give you the opportunity to gate a "courtesy" posit for the
source of any message you may have gated, but it is also so that
your IGate can know if a staiton is injecting packets directly
to the APRS-IS so you don't gate messages from the -IS to RF for
addressed to a station that would have received them directly on
the APRS-IS.
<br>
</blockquote>
<br>
Is this true for non-message packets, too? Because I hardly ever
see APRS messages in the logs, just beacons and telemetry all the
time. If APRS-IS server sends packets downstream only to stop me
from uploading the same packets back, it sounds like a weird
protocol design...
<br>
</blockquote>
<p>Lots of people think the APRS-IS is an intelligent network with
packet routing going on, but that is not the case. The APRS-IS is
simply a packet relay supporting RF communications via IGates.
And in order that an IGate (not the APRS-IS) can make informed
decisions, packets are delivered to it. This is to support #4 in
the "<span style="color: rgb(0, 0, 0); font-family: "Times
New Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-style: initial;
text-decoration-color: initial; display: inline !important;
float: none;">Gate message packets and associated posits to RF
if all of the following are true:</span>" list, specifically:</p>
<p><b><span style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
letter-spacing: normal; text-align: left; text-indent: 0px;
text-transform: none; white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-style:
initial; text-decoration-color: initial; display: inline
!important; float: none;">4. the receiving station has not
been heard via the Internet within a predefined time period.</span></b><b><br
style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
letter-spacing: normal; text-align: left; text-indent: 0px;
text-transform: none; white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-style:
initial; text-decoration-color: initial;">
</b><b><span style="color: rgb(0, 0, 0); font-family: "Times
New Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
letter-spacing: normal; text-align: left; text-indent: 0px;
text-transform: none; white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-style:
initial; text-decoration-color: initial; display: inline
!important; float: none;">A station is said to be heard via
the Internet if packets from the station contain TCPIP* or
TCPXX* in the header or if gated (3rd-party) packets are seen
on RF gated by the station and containing TCPIP or TCPXX in
the 3rd-party header (in other words, the station is seen on
RF as being an IGate).</span></b></p>
<blockquote type="cite"
cite="mid:0939ec24-700f-4a29-1ee5-0ba8b3a8558f@gmail.com">
<br>
I'd agree with Andrew KA2DDO: it seems there's some "minimal data
stream" offered to each Igate (and all IS-connected clients are
considered Igates). It probably serves some good purpose, but is
not well advertised.
<br>
</blockquote>
<p>In my experience and observations, this "minimal data stream" is
all based on which stations' packets you have delivered to the
APRS-IS. And these packets seem to be delivered for longer than
you'd expect as stations drive out of your RF coverage range. And
sometimes it seems like you get packets from the APRS-IS for
stations that are nowhere near your station, but if you check your
RF logs closely you'll likely find that you copied a packet via
some digipeater path from every station within the past hour or
two. Yes, it does seem to go on that long.<br>
</p>
<p>I've not written an APRS-IS server, nor have I looked at the
aprsc source code, but I have monitored the packets coming from
the APRS-IS to a a filter-less IGate and have been just as
confused as you seem to be. But in every case that I recall
researching, my IGate DID actually gate packets in "recent"
history for every station who's packets I subsequently received
from the APRS-IS.<br>
</p>
<p>I call it "WAD" - Working As Designed.<br>
</p>
Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
<br>
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